<?php
defined('ABSPATH') || exit();
final class APEARI_Workspace
{
    public static function normalize(array $data): array
    {
        $data += [
            'revision' => 0,
            'drafts' => [],
            'conversations' => [],
            'last' => null,
            'lastPage' => 'home',
            'history' => [],
            'future' => [],
            'remember' => false,
        ];
        $data['scopes'] = ['page' => true, 'theme' => false];
        $data['codeProposal'] = null;
        $data['historyArchive'] = [];
        $data['conversations'] = APEARI_Conversations::prune($data['conversations']);
        foreach (['history', 'future'] as $stack) {
            foreach ($data[$stack] as &$snapshot) {
                $snapshot['conversations'] = APEARI_Conversations::prune($snapshot['conversations'] ?? []);
            }
            unset($snapshot);
        }
        return $data;
    }
    public static function load(string $id)
    {
        $data = preg_match('/^[a-f0-9]{48}$/', $id) ? get_transient('apeari_session_' . $id) : false;
        if (
            !is_array($data) ||
            $data['user'] !== get_current_user_id() ||
            $data['theme'] !== get_stylesheet()
        ) {
            return new WP_Error('apeari_session', __('Sesja wygasła. Otwórz edytor ponownie.', 'apeari'), [
                'status' => 410,
            ]);
        }
        return self::normalize($data);
    }
    public static function keep(string $id, array $data): void
    {
        $data = self::normalize($data);
        set_transient('apeari_session_' . $id, $data, 2 * HOUR_IN_SECONDS);
        APEARI_Privacy::track('apeari_session_' . $id);
        APEARI_Conversations::remember($id, $data);
    }
    public static function mutate(string $id, callable $callback)
    {
        $lock = 'apeari_session_lock_' . md5($id);
        if ((int) get_option($lock) < time() - 120) {
            delete_option($lock);
        }
        if (!add_option($lock, time(), '', false)) {
            return new WP_Error('apeari_busy', __('Poprzedni zapis jeszcze trwa.', 'apeari'), [
                'status' => 409,
            ]);
        }
        try {
            $data = self::load($id);
            return is_wp_error($data) ? $data : $callback($data);
        } finally {
            delete_option($lock);
        }
    }
    public static function page(array $data, string $ref)
    {
        return $ref === $data['lastPage'] && preg_match('/^page:[1-9][0-9]*$/', $ref)
            ? APEARI_Documents::get($ref)
            : new WP_Error('apeari_scope', __('Edycja dotyczy wyłącznie wybranej strony.', 'apeari'), [
                'status' => 403,
            ]);
    }
    public static function public_state(array $data): array
    {
        $drafts = array_values($data['drafts']);
        foreach ($drafts as &$draft) {
            $draft['version'] = hash('sha256', $draft['content']);
        }
        return [
            'revision' => $data['revision'],
            'drafts' => $drafts,
            'scopes' => $data['scopes'],
            'lastPage' => $data['lastPage'],
            'conversations' => $data['conversations'],
            'history' => ['undo' => count($data['history']), 'redo' => count($data['future'])],
            'canRevert' => !empty($data['last']),
        ];
    }
    private static function snapshot(array &$data): void
    {
        $data['history'][] = ['drafts' => $data['drafts'], 'conversations' => $data['conversations']];
        $data['history'] = array_slice($data['history'], -12);
        $data['future'] = [];
    }
    public static function workspace(array $input)
    {
        $id = (string) ($input['sessionId'] ?? '');
        return self::mutate($id, static function ($data) use ($id, $input) {
            if (!empty($input['scopes']['theme'])) {
                return new WP_Error('apeari_scope', __('Ta edycja nie udostępnia motywu.', 'apeari'), [
                    'status' => 403,
                ]);
            }
            $ref = (string) ($input['pageRef'] ?? $data['lastPage']);
            if ($ref !== $data['lastPage'] && $data['drafts']) {
                return new WP_Error(
                    'apeari_dirty',
                    __('Opublikuj albo odrzuć szkic przed zmianą strony.', 'apeari'),
                    [
                        'status' => 409,
                    ],
                );
            }
            if ($ref !== $data['lastPage']) {
                $data['history'] = [];
                $data['future'] = [];
                $data['last'] = null;
            }
            $data['lastPage'] = $ref;
            $documents = [];
            if ($ref !== 'home') {
                $doc = self::page($data, $ref);
                if (is_wp_error($doc)) {
                    return $doc;
                }
                $doc['content'] = $data['drafts'][$ref]['content'] ?? $doc['content'];
                $doc['version'] = hash('sha256', $doc['content']);
                $documents[] = APEARI_Documents::public_data($doc);
            }
            self::keep($id, $data);
            return self::public_state($data) + ['documents' => $documents];
        });
    }
    public static function preview(array $input)
    {
        $id = (string) ($input['sessionId'] ?? '');
        return self::mutate($id, static function ($data) use ($id, $input) {
            if (($input['revision'] ?? -1) !== $data['revision']) {
                return APEARI_Context::stale();
            }
            if (!empty($input['clear'])) {
                self::snapshot($data);
                $data['drafts'] = [];
                ++$data['revision'];
                self::keep($id, $data);
                return self::public_state($data);
            }
            $items = $input['items'] ?? [$input];
            $thread = (string) ($input['threadKey'] ?? 'page:' . $data['lastPage']);
            if (
                !preg_match(
                    '/^(?:page:page:[1-9][0-9]*|element:page:[1-9][0-9]*:[0-9]+(?:\.[0-9]+)*)$/',
                    $thread,
                ) ||
                !str_starts_with(
                    $thread,
                    str_starts_with($thread, 'element:')
                        ? 'element:' . $data['lastPage'] . ':'
                        : 'page:' . $data['lastPage'],
                )
            ) {
                return new WP_Error('apeari_thread', __('Nieprawidłowa rozmowa.', 'apeari'), [
                    'status' => 422,
                ]);
            }
            if ($items === [] && isset($input['conversation'])) {
                APEARI_Conversations::store($data, $thread, $input['conversation']);
                ++$data['revision'];
                self::keep($id, $data);
                return self::public_state($data);
            }
            if (!is_array($items) || count($items) !== 1) {
                return new WP_Error('apeari_scope', __('Zapisz jeden dokument wybranej strony.', 'apeari'), [
                    'status' => 403,
                ]);
            }
            $item = $items[0];
            $doc = self::page($data, (string) ($item['ref'] ?? ''));
            if (is_wp_error($doc)) {
                return $doc;
            }
            $current = $data['drafts'][$doc['ref']]['content'] ?? $doc['content'];
            if (
                ($item['baseHash'] ?? '') !== $doc['hash'] ||
                ($item['baseVersion'] ?? '') !== hash('sha256', $current)
            ) {
                return APEARI_Context::stale();
            }
            if (!is_string($item['content'] ?? null)) {
                return new WP_Error('apeari_content', __('Brak treści.', 'apeari'), ['status' => 422]);
            }
            $safe = APEARI_Block_Policy::validate($doc['content'], $item['content']);
            if (is_wp_error($safe)) {
                return $safe;
            }
            $threads = self::remap_threads($data['conversations'], $input, $doc['ref']);
            if (is_wp_error($threads)) {
                return $threads;
            }
            self::snapshot($data);
            $data['conversations'] = $threads;
            if ($item['content'] === $doc['content']) {
                unset($data['drafts'][$doc['ref']]);
            } else {
                $data['drafts'][$doc['ref']] = [
                    'ref' => $doc['ref'],
                    'baseHash' => $doc['hash'],
                    'content' => $item['content'],
                ];
            }
            if (isset($input['conversation'])) {
                APEARI_Conversations::store($data, $thread, $input['conversation']);
            }
            ++$data['revision'];
            self::keep($id, $data);
            return self::public_state($data);
        });
    }
    public static function history(array $input)
    {
        $id = (string) ($input['sessionId'] ?? '');
        return self::mutate($id, static function ($data) use ($id, $input) {
            if (($input['revision'] ?? -1) !== $data['revision']) {
                return APEARI_Context::stale();
            }
            $from = ($input['action'] ?? '') === 'redo' ? 'future' : 'history';
            $to = $from === 'history' ? 'future' : 'history';
            if (!$data[$from]) {
                return new WP_Error('apeari_history', __('Brak zmiany do cofnięcia.', 'apeari'), [
                    'status' => 409,
                ]);
            }
            $next = array_pop($data[$from]);
            $data[$to][] = ['drafts' => $data['drafts'], 'conversations' => $data['conversations']];
            $data['drafts'] = $next['drafts'];
            $data['conversations'] = $next['conversations'];
            ++$data['revision'];
            self::keep($id, $data);
            return self::public_state($data);
        });
    }
    private static function remap_threads(array $original, array $input, string $ref)
    {
        $moves = $input['threadMoves'] ?? [];
        $deletes = $input['threadDeletes'] ?? [];
        $error = static fn() => new WP_Error(
            'apeari_thread',
            __('Nieprawidłowe przypisanie rozmów do bloków.', 'apeari'),
            ['status' => 422],
        );
        if (!is_array($moves) || !is_array($deletes) || count($moves) > 30 || count($deletes) > 30) {
            return $error();
        }
        $pattern = '/^element:' . preg_quote($ref, '/') . ':[0-9]+(?:\.[0-9]+)*$/';
        $destinations = [];
        foreach ($deletes as $key) {
            if (!is_string($key) || !preg_match($pattern, $key)) {
                return $error();
            }
        }
        foreach ($moves as $from => $to) {
            if (
                !is_string($from) ||
                !is_string($to) ||
                strlen($to) > 240 ||
                !isset($original[$from]) ||
                !preg_match($pattern, $from) ||
                !preg_match($pattern, $to) ||
                isset($destinations[$to])
            ) {
                return $error();
            }
            if (
                isset($original[$to]) &&
                !array_key_exists($to, $moves) &&
                !in_array($to, $deletes, true) &&
                $from !== $to
            ) {
                return $error();
            }
            $destinations[$to] = true;
        }
        $result = $original;
        foreach (array_merge(array_keys($moves), $deletes) as $key) {
            unset($result[$key]);
        }
        foreach ($moves as $from => $to) {
            $result[$to] = $original[$from];
        }
        return $result;
    }
    public static function write(array $input, bool $revert = false)
    {
        $id = (string) ($input['sessionId'] ?? '');
        return self::mutate($id, static function ($data) use ($id, $input, $revert) {
            if (($input['revision'] ?? -1) !== $data['revision']) {
                return APEARI_Context::stale();
            }
            $change = $revert ? $data['last'] : $data['drafts'][$data['lastPage']] ?? null;
            if (!$change || ($revert && $data['drafts'])) {
                return new WP_Error('apeari_empty', __('Brak zmiany do zapisania.', 'apeari'), [
                    'status' => 409,
                ]);
            }
            $doc = self::page($data, $change['ref']);
            if (is_wp_error($doc)) {
                return $doc;
            }
            if ($doc['hash'] !== ($revert ? $change['afterHash'] : $change['baseHash'])) {
                return APEARI_Context::stale();
            }
            require_once ABSPATH . 'wp-admin/includes/post.php';
            if (wp_check_post_lock((int) substr($doc['ref'], 5))) {
                return new WP_Error(
                    'apeari_locked',
                    __('Strona jest edytowana przez inną osobę.', 'apeari'),
                    [
                        'status' => 409,
                    ],
                );
            }
            $content = $revert ? $change['before'] : $change['content'];
            $safe = APEARI_Block_Policy::validate($doc['content'], $content);
            if (is_wp_error($safe)) {
                return $safe;
            }
            $saved = APEARI_Documents::save($doc, $content);
            if (is_wp_error($saved)) {
                return $saved;
            }
            clean_post_cache($saved);
            $next = APEARI_Documents::get($doc['ref']);
            if (
                is_wp_error($next) ||
                str_replace("\r\n", "\n", $next['content']) !==
                    str_replace("\r\n", "\n", APEARI_Documents::editable_content($content))
            ) {
                APEARI_Documents::save($doc, $doc['originalContent']);
                return new WP_Error(
                    'apeari_write',
                    __('WordPress nie zachował treści. Przywrócono poprzednią wersję.', 'apeari'),
                    ['status' => 500],
                );
            }
            $data['last'] = $revert
                ? null
                : ['ref' => $doc['ref'], 'before' => $doc['originalContent'], 'afterHash' => $next['hash']];
            $data['drafts'] = [];
            $data['history'] = [];
            $data['future'] = [];
            ++$data['revision'];
            self::keep($id, $data);
            return self::public_state($data);
        });
    }
}